Method for manufacturing electro-optical device, electro-optical device, and electronic apparatus

ABSTRACT

After a first wafer on which mirrors and terminals are formed and a second wafer for sealing are stacked and bonded together, the first wafer and the second wafer are diced to manufacture electro-optical devices. In doing so, in a second surface of the second wafer, recesses overlapping the mirrors in a plan view are previously formed, and also grooves overlapping the terminals in the plan view are previously formed. For this reason, when the second wafer is diced along the grooves by advancing a dicing blade for second wafer from a third surface of the second wafer, the dicing blade for second wafer can be prevented from coming into contact with the terminal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a Continuation of application Ser. No. 15/018,086 filed Feb. 8,2016, which claims the benefit of Japanese Application No. 2015-065932filed Mar. 27, 2015. The disclosures of the prior applications arehereby incorporated by reference herein in their entirety.

BACKGROUND

1. Technical Field

The present invention relates to a method for manufacturing anelectro-optical device including a mirror, an electro-optical device,and an electronic apparatus.

2. Related Art

As an electronic apparatus, for example, a projection type displaydevice or the like is known. The projection type display device or thelike modulates light emitted from a light source with a plurality ofmirrors (micromirrors) of an electro-optical device called a DMD(digital mirror device), and then enlarges and projects the modulatedlight with a projection optical system to thereby display an image ontoa screen. The electro-optical device used for the projection typedisplay device or the like includes an element substrate 1 as shown inFIG. 11D. The element substrate 1 includes, on one surface 1 s side,mirrors 50 and terminals 17 provided at positions next to the mirrors 50in a plan view. Moreover, the element substrate 1 is sealed by a spacer61 and a plate-like light-transmitting cover 71. The spacer 61 is bondedon the one surface 1 s side of the element substrate 1 so as to surroundthe mirrors 50 and the terminals 17 in the plan view. Thelight-transmitting cover 71 is supported to an edge of the spacer 61 onthe side opposite to the element substrate 1.

To manufacture the electro-optical device shown in FIG. 11D, forexample, a manufacturing method described below is proposed (see U.S.Pat. No. 6,856,014 B1). First, as shown in FIG. 11A, a first wafer 10including the mirrors 50 and the terminals 17 on one surface 10 s sideis formed, while a wafer 60 for spacer in which through-holes 66 areformed and a light-transmitting wafer 70 are stacked and bonded togetherto form a second wafer 20. As a result, the through-holes 66 serve asbottomed recesses 21. Next, as shown in FIG. 11B, the first wafer 10 andthe second wafer 20 are bonded together in a manner such that therecesses 21 overlap the mirrors 50 in a plan view. Next, as shown inFIG. 11C, a dicing blade 82 for second wafer is advanced to the secondwafer 20 from the side opposite to the first wafer 10 to dice the secondwafer 20 and expose the terminals 17. Next, as shown in FIG. 11D, thefirst wafer 10 is diced with a dicing blade 81 for first wafer to obtaina plurality of electro-optical devices 100.

In the manufacturing method shown in FIGS. 11A to 11D, however, thesecond wafer 20 is stacked in a state of being in contact with theterminals 17 as shown in FIG. 11B. Accordingly, when the second wafer 20is diced in the step shown in FIG. 11C, there is a problem in that thedicing blade 82 for second wafer may come in contact with the terminal17 and cause damage to the terminal 17.

SUMMARY

An advantage of some aspects of the invention is to provide a method formanufacturing an electro-optical device by which even when a stacked andbonded wafer is diced to expose a terminal, damage to the terminal canbe prevented, an electro-optical device, and an electronic apparatus.

A method for manufacturing an electro-optical device according to anaspect of the invention includes: preparing a first wafer including, ona first surface side, a first mirror, a first terminal, a second mirror,and a second terminal, the first terminal being provided at a positionnext to the first mirror in a plan view, the first terminal beingelectrically connected to a first drive element driving the firstmirror, the second mirror being located on the side opposite to thefirst mirror with respect to the first terminal, the second terminalbeing provided between the first terminal and the second mirror, thesecond terminal being electrically connected to a second drive elementdriving the second mirror; forming a second wafer including a secondsurface provided with a first recess having a light-transmitting bottomportion, a second recess having a light-transmitting bottom portion, anda groove between the first recess and the second recess; bonding thefirst surface of the first wafer and the second surface of the secondwafer together in a manner such that the first recess overlaps the firstmirror in the plan view, that the second recess overlaps the secondmirror in the plan view, and that the groove overlaps in the plan viewthe first terminal, the second terminal, and an area interposed betweenthe first terminal and the second terminal; dicing the second waferalong the groove by advancing a first dicing blade from a third surfaceof the second wafer on the side opposite to the second surface; anddicing the first wafer between the first terminal and the secondterminal with a second dicing blade.

In the aspect of the invention, after the first wafer and the secondwafer for sealing are bonded together, the first wafer and the secondwafer are diced to manufacture a plurality of electro-optical devices.In doing so, the groove overlapping in the plan view the first terminal,the second terminal, and the area interposed between the first terminaland the second terminal is previously formed in the second wafer inaddition to the first recess overlapping the first mirror and the secondrecess overlapping the second mirror. For this reason, the second waferis separated from the first terminal and the second terminal in a statewhere the first wafer and the second wafer are bonded together. For thisreason, the first terminal and the second terminal are not bonded to thesecond wafer. Moreover, in the dicing of the second wafer, the secondwafer is diced before the dicing blade for second wafer comes close tothe first terminal and the second terminal. Accordingly, the dicingblade for second wafer is less likely to come into contact with thefirst terminal and the second terminal and cause damage to the firstterminal and the second terminal. Hence, the yield of theelectro-optical device can be improved.

The invention may employ a configuration in which the thickness of thesecond dicing blade is smaller than the thickness of the first dicingblade and in the dicing of the first wafer, the first wafer is diced byadvancing the second dicing blade to the first wafer from the secondsurface side. According to the configuration, after the dicing of thesecond wafer, a step of turning over a stacked body of the first waferand the second wafer is not necessary before the dicing of the firstwafer.

The invention may employ a configuration in which the thickness of thefirst dicing blade is greater than the width of the groove. Anelectro-optical device manufactured according to this configurationincludes: an element substrate including a mirror and a terminal on afirst surface side, the terminal being provided at a position next tothe mirror in a plan view, the terminal being electrically connected toa drive element driving the mirror; and a sealing member including aspacer and a plate-like light-transmitting cover, the spacer beingbonded on the first surface side of the element substrate andsurrounding the mirror in the plan view, the light-transmitting coverbeing supported to an edge of the spacer on the side opposite to an edgethereof facing the element substrate, the light-transmitting coveroverlapping the mirror in the plan view, wherein in a side surface ofthe sealing member, a second portion closer to the element substratethan a first portion projects opposite to the mirror beyond the firstportion. According to the configuration, it is easy to connect theterminal provided on the substrate with another terminal by wirebonding. Also in this case, since the area (bonding width) of bondingthe sealing member with the substrate is not reduced, a sealing propertybetween the sealing member and the substrate is not reduced.

The invention may employ a configuration in which the thickness of thefirst dicing blade is smaller than the width of the groove. Anelectro-optical device manufactured according to this configurationincludes: an element substrate including a mirror and a terminal on afirst surface side, the terminal being provided at a position next tothe mirror in a plan view, the terminal being electrically connected toa drive element driving the mirror; and a sealing member including aspacer and a plate-like light-transmitting cover, the spacer beingbonded on the first surface side of the element substrate andsurrounding the mirror in the plan view, the light-transmitting coverbeing supported to an edge of the spacer on the side opposite to an edgethereof facing the element substrate, the light-transmitting coveroverlapping the mirror in the plan view, wherein in a side surface ofthe sealing member, a second portion closer to the element substratethan a first portion is recessed to the mirror side beyond the firstportion.

In the aspect of the invention, it is preferable that a multistage bladeincluding the second dicing blade and the first dicing blade stackedtogether in a thickness direction is used, and that the dicing of thesecond wafer and the dicing of the first wafer are continuouslyperformed by advancing the multistage blade to the first wafer from thesecond wafer side.

The invention may employ a configuration in which the forming of thesecond wafer includes forming a first through-hole, a secondthrough-hole, and the groove in a third wafer, and stacking and bondinga light-transmitting fourth wafer on and to a surface of the third waferon the side opposite to the side where the groove is opened.

The invention may employ a configuration in which the forming of thesecond wafer includes forming a first through-hole and a secondthrough-hole in a third wafer, stacking and bonding the third wafer anda light-transmitting fourth wafer together, and forming the groove in asurface of the third wafer on the side opposite to a surface thereofbonded with the fourth wafer.

The electro-optical device to which the invention is applied can be usedfor various types of electronic apparatuses, and in this case, theelectronic apparatus is provided with a light source unit thatirradiates the mirror with light source light. Moreover, when aprojection type display device is configured as the electronicapparatus, the electronic apparatus is further provided with aprojection optical system that projects light modulated by the mirror.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a schematic view showing an optical system of a projectiontype display device as an electronic apparatus to which the invention isapplied.

FIGS. 2A and 2B are explanatory views schematically showing a basicconfiguration of an electro-optical device to which the invention isapplied.

FIGS. 3A and 3B are explanatory views schematically showing a crosssection taken along the line A-A′ at a main portion of theelectro-optical device to which the invention is applied.

FIG. 4 is a cross-sectional view of the electro-optical device to whichthe invention is applied.

FIGS. 5A to 5D are step cross-sectional views showing a method formanufacturing the electro-optical device to which the invention isapplied.

FIGS. 6A to 6F are step views showing a method for manufacturing asecond wafer, etc. used for the manufacture of the electro-opticaldevice to which the invention is applied.

FIGS. 7A to 7C are step cross-sectional views showing a step of sealinga substrate with a substrate and a sealing resin in the manufacturingprocess of the electro-optical device to which the invention is applied.

FIGS. 8A and 8B are explanatory views showing Modified Examples 1 and 2of the method for manufacturing the electro-optical device to which theinvention is applied.

FIGS. 9A and 9B are explanatory views showing Modified Example 3 of themethod for manufacturing the electro-optical device to which theinvention is applied.

FIGS. 10A to 10D are explanatory views showing Modified Example 4 of themethod for manufacturing the electro-optical device to which theinvention is applied.

FIGS. 11A to 11D are step cross-sectional views showing a method formanufacturing an electro-optical device according to a reference exampleof the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

An embodiment of the invention will be described with reference to thedrawings. In the following description, a projection type display devicewill be described as an electronic apparatus to which the invention isapplied. In the drawings to be referred to in the following description,layers or members are shown in different scales so that each of thelayers or members has a recognizable size on the drawings. The numbersof mirrors, etc. shown in the drawings are set in a manner such that themirror, etc. have a recognizable size on the drawings, but a largernumber of mirrors, etc. than those shown in the drawings may beprovided.

Projection Type Display Device as Electronic Apparatus

FIG. 1 is a schematic view showing an optical system of a projectiontype display device as an electronic apparatus to which the invention isapplied. The projection type display device 1000 shown in FIG. 1includes a light source unit 1002, an electro-optical device 100 thatmodulates light emitted from the light source unit 1002 in response toimage information, and a projection optical system 1004 that projects asa projection image the light modulated by the electro-optical device 100onto a projected object 1100 such as a screen. The light source unit1002 includes a light source 1020 and a color filter 1030. The lightsource 1020 emits white light. The color filter 1030 emits lights ofrespective colors as the color filter rotates. The electro-opticaldevice 100 modulates incident light at the timing in synchronizationwith the rotation of the color filter 1030. Instead of the color filter1030, a phosphor substrate that converts the light emitted from thelight source 1020 into lights of respective colors may be used.Moreover, the light source unit 1002 and the electro-optical device 100may be provided for each of lights of respective colors.

Basic Configuration of Electro-Optical Device 100

FIGS. 2A and 2B are explanatory views schematically showing a basicconfiguration of the electro-optical device 100 to which the inventionis applied, in which FIG. 2A is an explanatory view showing a mainportion of the electro-optical device 100, and FIG. 2B is an explodedperspective view of a main portion of the electro-optical device 100.FIGS. 3A and 3B are explanatory views schematically showing a crosssection taken along the line A-A′ at the main portion of theelectro-optical device 100 to which the invention is applied, in whichFIG. 3A is an explanatory view schematically showing a state where amirror is inclined to one side, and FIG. 3B is an explanatory viewschematically showing a state where the mirror is inclined to the otherside.

As shown in FIGS. 2A to 3B, the electro-optical device 100 includes aplurality of mirrors 50 disposed in a matrix on one surface 1 s (firstsurface) side of an element substrate 1. The mirrors 50 are separatedfrom the element substrate 1. The element substrate 1 is, for example, asilicon substrate. The mirror 50 is, for example, a micromirror having aplanar size with a side length of, for example, from 10 μm to 30 μm. Themirrors 50 are arranged in, for example, from an 800×600 array to a1028×1024 array. One mirror 50 corresponds to one pixel in an image.

The surface of the mirror 50 is a reflective surface made of areflective metal film such as aluminum. The electro-optical device 100includes a first level portion 100 a including a substrate-side biaselectrode 11 and substrate-side address electrodes 12 and 13 all ofwhich are formed on the one surface 1 s of the element substrate 1, asecond level portion 100 b including elevated address electrodes 32 and33 and a hinge 35, and a third level portion 100 c including the mirrors50. In the first level portion 100 a, an addressing circuit 14 is formedin the element substrate 1. The addressing circuit 14 includes memorycells for selectively controlling operation of each of the mirrors 50,and wiring lines 15 of word lines and bit lines. The addressing circuit14 has a circuit configuration similar to a RAM (Random Access Memory)including a CMOS circuit 16.

The second level portion 100 b includes the elevated address electrodes32 and 33, the hinge 35, and a mirror post 51. The elevated addresselectrodes 32 and 33 conduct with the substrate-side address electrodes12 and 13 via electrode posts 321 and 331, and are supported by thesubstrate-side address electrodes 12 and 13. Hinge arms 36 and 37 extendfrom both ends of the hinge 35. The hinge arms 36 and 37 conduct withthe substrate-side bias electrode 11 via an arm post 39, and aresupported by the substrate-side bias electrode 11. The mirror 50conducts with the hinge 35 via the mirror post 51, and is supported bythe hinge 35. Accordingly, the mirror 50 conducts with thesubstrate-side bias electrode 11 via the mirror post 51, the hinge 35,the hinge arms 36 and 37, and the arm post 39, so that a bias voltage isapplied from the substrate-side bias electrode 11 to the mirror 50. Atthe tips of the hinge arms 36 and 37, stoppers 361, 362, 371, and 372that come into contact with the mirror 50 when the mirror 50 is inclinedto thereby prevent contact between the mirror 50 and the elevatedaddress electrodes 32 and 33 are formed.

The elevated address electrodes 32 and 33 constitute a drive element 30that generates an electrostatic force between the mirror 50 and theelevated address electrodes 32 and 33 to drive the mirror 50 in aninclined manner. In some cases, the substrate-side address electrodes 12and 13 are configured also so as to generate an electrostatic forcebetween the mirror 50 and the substrate-side address electrodes 12 and13 to drive the mirror 50 in an inclined manner. In this case, the driveelement 30 is composed of the elevated address electrodes 32 and 33 andthe substrate-side address electrodes 12 and 13. The hinge 35 is twistedwhen the mirror 50 is inclined so as to be attracted to the elevatedaddress electrode 32 or the elevated address electrode 33 by theapplication of a drive voltage to the elevated address electrodes 32 and33 as shown in FIGS. 3A and 3B, so that the hinge 35 provides a force toreturn the mirror 50 to its parallel posture relative to the elementsubstrate 1 when the attractive force for the mirror 50 disappears withthe stop of the application of the drive voltage to the elevated addresselectrodes 32 and 33.

In the electro-optical device 100, when the mirror 50 is inclined to theelevated address electrode 32 side as one side as shown in FIG. 3A forexample, an on-state is established in which the light emitted from thelight source unit 1002 is reflected by the mirror 50 toward theprojection optical system 1004. In contrast, when the mirror 50 isinclined to the elevated address electrode 33 side as the other side asshown in FIG. 3B, an off-state is established in which the light emittedfrom the light source unit 1002 is reflected by the mirror 50 toward alight-absorbing device 1005. In the off-state, the light is notreflected toward the projection optical system 1004. Such driving isperformed in each of the plurality of mirrors 50, and as a result, thelight emitted from the light source unit 1002 is modulated by theplurality of mirrors 50 into image light, the image light is projectedfrom the projection optical system 1004, and thus an image is displayed.

A flat plate-like yoke facing the substrate-side address electrodes 12and 13 may be provided integrally with the hinge 35, and anelectrostatic force acting between the substrate-side address electrodes12 and 13 and the yoke may be used in addition to the electrostaticforce generated between the elevated address electrodes 32 and 33 andthe mirror 50 to drive the mirror 50.

Sealing Structure of Electro-Optical Device 100

FIG. 4 is a cross-sectional view of the electro-optical device 100 towhich the invention is applied. As shown in FIG. 4, in theelectro-optical device 100 of the embodiment, the element substrate 1 inwhich the plurality of mirrors 50 described with reference to FIGS. 2Ato 3B are formed is sealed at the one surface 1 s with a sealing member75 composed of a frame-like spacer 61 and a flat plate-likelight-transmitting cover 71 having a light-transmitting property.Thereafter, the element substrate 1 is fixed to a substrate mountportion 93 of a substrate, and then sealed with a sealing resin 98. Inthe substrate 90, the substrate mount portion 93 is a bottomed recesssurrounded by a side plate portion 92. The element substrate 1 is fixedto a bottom plate portion 91 of the substrate 90 with an adhesive 97.

Here, an edge 61 e of the spacer 61 on the element substrate 1 side isbonded to the one surface 1 s of the element substrate 1. Thelight-transmitting cover 71 is bonded to an edge 61 f that is an edge ofthe spacer 61 on the side opposite to the edge facing the elementsubstrate 1, and is supported to the edge 61 f. In this state, thelight-transmitting cover 71 faces the surfaces of the mirrors 50 at aposition spaced from the mirrors 50 with a predetermined distance.Accordingly, light passes through the light-transmitting cover 71 and isincident on the mirror 50, and thereafter, the light reflected by themirror 50 passes through the light-transmitting cover 71 and is emitted.In the embodiment, the light-transmitting cover 71 is made of glass. Thespacer 61 may be made of glass, silicon, metal, or resin, and in theembodiment, a glass substrate or a silicon substrate is used as thespacer 61. The sealing member 75 is not limited to that formed ofseparated bodies (a plurality of members) like the spacer 61 and thelight-transmitting cover 71, and the spacer 61 and thelight-transmitting cover 71 may be formed into one body.

On the one surface 1 s of the element substrate 1, a plurality ofterminals 17 are formed at an edge (outside the spacer 61) notoverlapping the mirrors 50. In the embodiment, the terminals 17 aredisposed in two rows so as to interpose the mirrors 50 therebetween. Aportion of the plurality of terminals 17 is electrically connected tothe elevated address electrodes 32 and 33 (the drive element 30) via theaddressing circuit 14 or the substrate-side address electrodes 12 and 13described with reference to FIGS. 2A to 3B. Another portion of theplurality of terminals 17 is electrically connected to the mirrors 50via the addressing circuit 14, the substrate-side bias electrode 11, andthe hinge 35 described with reference to FIGS. 2A to 3B. Yet anotherportion of the plurality of terminals 17 is electrically connected to adriver circuit, etc. provided in front of the addressing circuit 14described with reference to FIGS. 2A to 3B.

Here, since the terminals 17 are in an open state on the side oppositeto the element substrate 1, the terminals 17 are electrically connectedwith internal terminals 94 formed on a surface 91 s of the bottom plateportion 91 of the substrate 90 on the element substrate 1 side by meansof wires 99 for wire bonding. The bottom plate portion 91 of thesubstrate 90 is a multilayer wiring board, and the internal terminals 94conduct with external terminals 96 formed on an outer surface 91 t ofthe bottom plate portion 91 on the side opposite to the elementsubstrate 1 via a multilayer wiring portion 95 composed of through-holesand wiring lines formed in the bottom plate portion 91.

The sealing resin 98 is provided on the inside (recess) of the sideplate portion 92 of the substrate 90. The sealing resin 98 covers thewires 99, junctions between the wires 99 and the terminals 17, junctionsbetween the wires 99 and the internal terminals 94, the perimeter of theelement substrate 1, and the perimeter of a bonding portion of thespacer 61 and the element substrate 1. The sealing resin 98 also coversthe side surface of the light-transmitting cover 71 up to the middleportion in the thickness direction.

Method for Manufacturing Electro-Optical Device 100

A method for manufacturing the electro-optical device 100 to which theinvention is applied will be described with reference to FIGS. 5A to 7C.FIGS. 5A to 5D are step cross-sectional views showing the method formanufacturing the electro-optical device 100 to which the invention isapplied. FIGS. 6A to 6F are step views showing a method formanufacturing a second wafer 20, etc. used for the manufacture of theelectro-optical device 100 to which the invention is applied. In FIGS.6A to 6F, a plan view of a wafer in each step is shown, and also acutaway end view thereof is shown below the plan view. FIGS. 7A to 7Care step cross-sectional views showing a step of sealing the elementsubstrate 1 with the substrate 90 and the sealing resin 98 in themanufacturing process of the electro-optical device 100 to which theinvention is applied. The mirrors are not illustrated in FIG. 6B.Compared to FIG. 4, the number of mirrors 50 is reduced in FIGS. 5A to5D, in which three mirrors 50 are shown on the assumption that threemirrors 50 are formed on one element substrate 1.

In the embodiment, a plurality of element substrates 1, etc. areobtained from a wafer. For this reason, in the following description,for example, the mirror 50 and the terminal 17 that are formed in anarea from which one substrate is obtained, in the plurality of elementsubstrates 1 obtained from a wafer, are denoted by “a” appended to thereference numerals, and described as “first mirror 50 a” and “firstterminal 17 a”, respectively. Moreover, in the plurality of elementsubstrates 1, for example, the mirror 50 and the terminal 17 that areformed in an area next to the area where the first mirror 50 a and thefirst terminal 17 a are formed are denoted by “b” appended to thereference numerals, and described as “second mirror 50 b” and “secondterminal 17 b”, respectively. However, when it is not necessary tospecify any element substrate 1, the components are described withoutappending the “a” or “b” to the reference numerals.

To manufacture the electro-optical device 100 of the embodiment, asshown in FIGS. 5A, 6A, and 6B, a large-sized first wafer 10 from which aplurality of element substrates 1 can be obtained is prepared in afirst-wafer preparing step. The first wafer 10 includes, on one surface10 s (first surface) thereof, the mirrors 50 and the terminals 17 formedin each of areas by which the element substrate 1 is divided. Theterminals 17 are formed at positions next to the mirrors 50 in a planview (e.g., in a plan view when viewed from the one surface 10 s side ofthe first wafer 10), and electrically connected to the drive element 30(see FIGS. 2A to 3B) that drives the mirror 50.

On the one surface 10 s of the first wafer 10, the first mirrors 50 aare formed, and also the first terminals 17 a electrically connected toa first drive element 30 a (see FIGS. 2A to 3B) that drives the firstmirrors 50 a are formed at positions next to the first mirror 50 a inthe plan view. Moreover, on the one surface 10 s of the first wafer 10,the second mirrors 50 b are formed on the side opposite to the firstmirrors 50 a with respect to the first terminal 17 a, and also thesecond terminals 17 b electrically connected to a second drive element30 b (see FIGS. 2A to 3B) that drives the second mirror 50 b are formedbetween the first terminals 17 a and the second mirrors 50 b. Forexample, as shown in FIGS. 5A, 6A, and 6B, the first wafer 10 may beprepared by forming, on the one surface 10 s of the large-sized firstwafer 10 from which a plurality of element substrates 1 can be obtained,the mirrors 50 in each of areas by which the element substrate 1 isdivided, and also forming the terminals 17 electrically connected to thedrive element 30 (see FIGS. 2A to 3B) that drives the mirrors 50 atpositions next to the mirrors 50 in the plan view.

As shown in FIG. 5A, a large-sized second wafer 20 from which aplurality of spacers 61 and a plurality of light-transmitting covers 71can be obtained is prepared in a second-wafer forming step. On a secondsurface 20 s composed of one surface of the second wafer 20, a recess 21having a light-transmitting bottom portion is formed in each of areas bywhich the spacer 61 and the light-transmitting cover 71 are divided, andalso bottomed grooves 22 extending in two directions that intersect eachother at right angles and surrounding each of the plurality of recesses21 are formed. One of the plurality of recesses 21 is a first recess 21a, and the recess 21 next to the first recess 21 a is a second recess 21b. Accordingly, the first recess 21 a having the light-transmittingbottom portion, the second recess 21 b having the light-transmittingbottom portion, and the bottomed grooves 22 extending along and betweenthe first recess 21 a and the second recess 21 b are formed in thesecond surface 20 s of the second wafer 20.

In the formation of the second wafer 20, for example, steps shown inFIG. 6C to 6F are performed in the second-wafer forming step. First, asshown in FIG. 6C, a light-transmitting wafer 70 (fourth wafer) fromwhich a plurality of light-transmitting covers 71 can be obtained isprepared. Moreover, as shown in FIG. 6D, after a wafer 60 (third wafer)for spacer from which a plurality of spacers 61 can be obtained isprepared, through-holes 66 for constituting the recesses 21 are formedby a process such as etching in the wafer 60 for spacer in a first step.One of the plurality of through-holes 66 is a first through-hole 66 afor constituting the first recess 21 a, and the through-hole 66 next tothe first through-hole 66 a is a second through-hole 66 b forconstituting the second recess 21 b. Next, as shown in FIG. 6E, thebottomed grooves 22 extending in the two directions that intersect eachother at right angles and surrounding each of the plurality of recesses21 are formed by a process such as half-etching. In the first step, thegrooves 22 are formed after the through-holes 66 are formed, but thethrough-holes 66 may be formed after the grooves 22 are formed. In theembodiment, the light-transmitting cover 71 is made of glass. The wafer60 for spacer may be made of glass, silicon, metal, or resin.

Next, in a second step as shown in FIG. 6F, the light-transmitting wafer70 is stacked on and bonded to a surface 60 t of the wafer 60 for spaceron the side opposite to a surface 60 s thereof in which the grooves 22are opened. As a result, the second wafer 20 including the wafer 60 forspacer and the light-transmitting wafer 70 stacked together is formed.In the second wafer 20, the surface 60 s of the wafer 60 for spacerconstitutes the second surface 20 s of the second wafer 20, while asurface of the light-transmitting wafer 70 on the side opposite to thewafer 60 for spacer constitutes a third surface 20 t of the second wafer20. Moreover, one open end of the through-hole 66 (the firstthrough-hole 66 a and the second through-hole 66 b) is closed by thelight-transmitting wafer 70, so that the recess 21 (the first recess 21a and the second recess 21 b) having the light-transmitting bottomportion is formed.

Next, in a bonding step as shown in FIG. 5B, the one surface 10 s of thefirst wafer 10 and the second surface 20 s of the second wafer 20 arebonded together in a manner such that the recesses 21 overlap themirrors 50 in a plan view (e.g., in a plan view when the first wafer 10is viewed from the one surface 10 s side), and that the grooves 22overlap the terminals 17. As a result, the first recess 21 a overlapsthe first mirrors 50 a in the plan view, the second recess 21 b overlapsthe second mirrors 50 b in the plan view, and a common groove 22overlaps in the plan view the first terminal 17 a, the second terminal17 b, and an area interposed between the first terminal 17 a and thesecond terminal 17 b. In this state, a portion interposed between thefirst recess 21 a and the groove 22 in the second wafer 20 is bondedbetween the first mirror 50 a and the first terminal 17 a, and a portioninterposed between the second recess 21 b and the groove 22 in thesecond wafer 20 is bonded between the second mirror 50 b and the secondterminal 17 b. Accordingly, the first terminal 17 a and the secondterminal 17 b are not bonded to the second wafer 20.

Next, in a second-wafer dicing step as shown in FIG. 5C, the secondwafer 20 is diced along the grooves 22 by advancing a dicing blade 82for second wafer (first dicing blade) from the third surface 20 tcomposed of a surface of the second wafer 20 on the side opposite to thesecond surface 20 s. As a result, the second wafer 20 is divided, a flatplate portion divided from the light-transmitting wafer 70 in the secondwafer 20 constitutes the light-transmitting cover 71, and a frameportion divided from the wafer 60 for spacer in the second wafer 20constitutes the spacer 61. In the embodiment, a thickness W2 of thedicing blade 82 for second wafer is equal to a width W0 of the groove22.

Next, in a first-wafer dicing step as shown in FIG. 5D, the first wafer10 is diced with a dicing blade 81 for first wafer (second dicing blade)along an area (area interposed between the first terminal 17 a and thesecond terminal 17 b) by which the element substrate 1 is divided in thefirst wafer 10. As a result, the first wafer 10 is diced between thefirst terminal 17 a and the second terminal 17 b. In the embodiment, athickness W1 of the dicing blade 81 for first wafer is smaller than thethickness W2 of the dicing blade 82 for second wafer. Accordingly, inthe first-wafer dicing step, the first wafer 10 is diced by advancingthe dicing blade 81 for first wafer to the first wafer 10 from thesecond wafer 20 side into a cut portion (between the light-transmittingcovers 71 next to each other and between the spacers 61 next to eachother) of the second wafer 20.

As a result, a plurality of electro-optical devices 100 in which the onesurface 1 s of the element substrate 1 including a plurality of mirrors50 formed thereon is sealed by the spacer 61 and the light-transmittingcover 71 are manufactured. When the electro-optical device 100 isfurther sealed by the substrate 90 and the sealing resin 98 as shown inFIG. 4, steps shown in FIGS. 7A to 7C are performed.

First, as shown in FIG. 7A, after the substrate 90 having the substratemount portion 93 as a recess surrounded by the side plate portion 92 isprepared, the element substrate 1 is fixed to the bottom portion of thesubstrate mount portion 93 with the adhesive 97 as shown in FIG. 7B.Next, as shown in FIG. 7C, the terminals 17 of the element substrate 1and the internal terminals 94 of the substrate 90 are electricallyconnected by means of the wires 99 for wire bonding. Next, as shown inFIG. 4, after the sealing resin 98 is injected inside the side plateportion 92 of the substrate 90, the sealing resin 98 is cured to sealthe element substrate 1 with the sealing resin 98. As a result, theelectro-optical device 100 in which the element substrate 1 is sealed bythe spacer 61, the light-transmitting cover 71, the substrate 90, andthe sealing resin 98 can be obtained.

Principal Advantageous Effects of the Embodiment

In the embodiment as has been described above, after the first wafer 10and the second wafer 20 for sealing are bonded together, the first wafer10 and the second wafer 20 are diced to manufacture a plurality ofelectro-optical devices 100. In doing so, the groove 22 overlapping inthe plan view the first terminal 17 a, the second terminal 17 b, and thearea interposed between the first terminal 17 a and the second terminal17 b is previously formed in the second wafer 20. Accordingly, in theembodiment, the second wafer 20 is separated from the first terminal 17a and the second terminal 17 b in a state where the first wafer 10 andthe second wafer 20 are bonded together. For this reason, the firstterminal 17 a and the second terminal 17 b are not bonded to the secondwafer 20. Moreover, in the second-wafer dicing step, the second wafer 20is diced before the dicing blade 82 for second wafer comes close to thefirst terminal 17 a and the second terminal 17 b. Accordingly, thedicing blade 82 for second wafer is less likely to come into contactwith the first terminal 17 a and the second terminal 17 b and causedamage to the first terminal 17 a and the second terminal 17 b. Hence,the yield of the electro-optical device 100 can be improved.

Moreover, in the embodiment, the first-wafer dicing step and thesecond-wafer dicing step are separately performed. Therefore, lesschipping or cracking occurs in the first wafer 10.

Modified Examples 1 and 2 of the Invention

FIGS. 8A and 8B are explanatory views showing Modified Examples 1 and 2of the method for manufacturing the electro-optical device 100 to whichthe invention is applied, in which FIG. 8A is a cross-sectional view ofthe electro-optical device 100 according to Modified Examples 1, andFIG. 8B is a cross-sectional view of the electro-optical device 100according to Modified Examples 2. In the embodiment described above, thethickness W2 of the dicing blade 82 for second wafer shown in FIG. 5C isequal to the width W0 of the groove 22. Therefore, as shown in FIG. 4,the side surface 71 w of the light-transmitting cover 71 and an outerside surface 61 w of the spacer 61 on the side opposite to the mirror 50form a continuous plane over the entire side surface.

In contrast, in Modified Examples 1, the thickness W2 of the dicingblade 82 for second wafer shown in FIG. 5C is greater than the width W0of the groove 22. For this reason, as shown in FIG. 8A, in the sidesurface 71 w of the light-transmitting cover 71 and the outer sidesurface 61 w of the spacer 61 as a surface on the side opposite to asurface facing the mirror 50, the edge 61 e of the spacer 61 on theelement substrate 1 side is a projection 61 g that projects opposite tothe mirror 50 beyond a portion of the spacer 61 located on the sideopposite to the element substrate 1. In other words, the projection 61g, which is a second portion closer to the element substrate 1 than afirst portion and projects opposite to the mirror 50 beyond the firstportion, is formed on the side surface (the side surface 71 w of thelight-transmitting cover 71 and the outer side surface 61 w of thespacer 61) of the sealing member 75 composed of the spacer 61 and thelight-transmitting cover 71. For this reason, since the terminal 17 isgreatly opened on the side opposite to the element substrate 1, it iseasy to perform wire bonding. Also in this case, since the area (bondingwidth) of bonding the spacer 61 with the element substrate 1 is notreduced, a sealing property between the spacer 61 and the elementsubstrate 1 is not reduced.

In Modified Examples 2, on the other hand, the thickness W2 of thedicing blade 82 for second wafer shown in FIG. 5C is smaller than thewidth W0 of the groove 22. For this reason, as shown in FIG. 8B, in theside surface 71 w of the light-transmitting cover 71 and the outer sidesurface 61 w of the spacer 61 on the side opposite to the mirror 50, theedge 61 e of the spacer 61 on the element substrate 1 side is a recess61 h recessed to the mirror 50 side beyond the portion of the spacer 61located on the side opposite to the element substrate 1. In other words,the recess 61 h, which is a second portion closer to the elementsubstrate 1 than a first portion and recessed to the mirror 50 sidebeyond the first portion, is formed in the side surface (the sidesurface 71 w of the light-transmitting cover 71 and the outer sidesurface 61 w of the spacer 61) of the sealing member 75 composed of thespacer 61 and the light-transmitting cover 71. Also in this case, sincethe area (bonding width) of bonding the spacer 61 with thelight-transmitting cover 71 is not reduced, a sealing property betweenthe spacer 61 and the light-transmitting cover 71 is not reduced.

Modified Example 3 of the Invention

FIGS. 9A and 9B are explanatory views showing Modified Example 3 of themethod for manufacturing the electro-optical device 100 to which theinvention is applied, in which FIG. 9A is an explanatory view of adicing blade used in Modified Examples 3, and FIG. 9B is an explanatoryview showing a state of dicing the first wafer 10 and the second wafer20 with the dicing blade used in Modified Examples 3.

In Modified Example 3, as shown in FIGS. 9A and 9B, a multistage blade85 including the dicing blade 81 for first wafer and the dicing blade 82for second wafer concentrically stacked together in the thicknessdirection is used in the second-wafer dicing step and the first-waferdicing step shown in FIGS. 5C and 5D. In the multistage blade 85, thedicing blade 81 for first wafer has a diameter greater than the dicingblade 82 for second wafer, and the dicing blade 82 for second waferprojects from both surfaces of the dicing blade 81 for first wafer.Accordingly, the thickness W2 of the dicing blade 82 for second wafer isgreater than the thickness W1 of the dicing blade 81 for first wafer.According to the multistage blade 85, the second-wafer dicing step andthe first-wafer dicing step can be continuously performed in the samestep by advancing the multistage blade 85 to the first wafer 10 from thesecond wafer 20 side.

Although the thickness W2 of the dicing blade 82 for second wafer isgreater than the width W0 of the groove 22 in the step shown in FIG. 9B,the thickness W2 of the dicing blade 82 for second wafer may be smallerthan the width W0 of the groove 22.

Modified Example 4 of the Invention

FIGS. 10A to 10D are explanatory views showing Modified Example 4 of themethod for manufacturing the electro-optical device 100 to which theinvention is applied, and FIGS. 10A to 10D are step views showing amethod for manufacturing the second wafer 20, etc. used for themanufacture of the electro-optical device 100. In FIGS. 10A to 10D, aplan view of a wafer in each step is shown, and also a cutaway end viewthereof is shown below the plan view.

In Modified Example 4, in the second-wafer forming step of forming thesecond wafer 20 shown in FIG. 5A, the light-transmitting wafer 70 fromwhich a plurality of light-transmitting covers 71 can be obtained isfirst prepared as shown in FIG. 10A. Moreover, as shown in FIG. 10B,after the wafer 60 for spacer from which a plurality of spacers 61 canbe obtained is prepared, the through-holes 66 for constituting therecesses 21 are formed in the wafer 60 for spacer by a process such asetching in a first step. One of the plurality of through-holes 66 is thefirst through-hole 66 a for constituting the first recess 21 a, and thethrough-hole 66 next to the first through-hole 66 a is the secondthrough-hole 66 b for constituting the second recess 21 b.

In a second step, the wafer 60 for spacer and the light-transmittingwafer 70 are stacked and bonded together. As a result, one open end ofthe through-hole 66 (the first through-hole 66 a and the secondthrough-hole 66 b) is closed by the light-transmitting wafer 70, so thatthe recess 21 (the first recess 21 a and the second recess 21 b) havingthe light-transmitting bottom portion is formed.

Next, in a third step, the bottomed grooves 22 extending in the twodirections that intersect each other at right angles and surroundingeach of the plurality of recesses 21 are formed by a process such ashalf-etching in the surface 60 s of the wafer 60 for spacer on the sideopposite to the surface bonded with the light-transmitting wafer 70. Asa result, the second wafer 20 including the wafer 60 for spacer and thelight-transmitting wafer 70 stacked together is formed. In the secondwafer 20, the surface 60 s of the wafer 60 for spacer constitutes thesecond surface 20 s of the second wafer 20, and the surface of thelight-transmitting wafer 70 on the side opposite to the wafer 60 forspacer constitutes the third surface 20 t of the second wafer 20.

Modified Example 5 of the Invention

In the embodiment described above, the recess 21 (the through-hole 66)and the groove 22 are formed by a process such as etching. However, thesecond wafer 20 in which the recesses 21 and the grooves 22 are formedmay be formed by molding, etc. Moreover, the second wafer 20 may beformed using the wafer 60 for spacer in which the through-holes 66 andthe grooves 22 are formed by molding, etc.

Another Embodiment

In the embodiment described above, a circular wafer is used. However,the planar shape of a wafer may be rectangular, etc.

What is claimed is:
 1. An electro-optical device comprising: an elementsubstrate including a mirror and a terminal on a first surface side, theterminal being provided at a position next to the mirror in a plan view,the terminal being electrically connected to a drive element driving themirror; and a sealing member including a spacer and a plate-likelight-transmitting cover, the spacer being bonded on the first surfaceside of the element substrate and surrounding the mirror in the planview, the light-transmitting cover being supported to an edge of thespacer on the side opposite to an edge thereof facing the elementsubstrate, the light-transmitting cover overlapping the mirror in theplan view, wherein in a side surface of the sealing member, a secondportion closer to the element substrate than a first portion projectsopposite to the mirror beyond the first portion.
 2. The electro-opticaldevice according to claim 1, wherein the first portion projects oppositeto the mirror beyond the first portion beyond an edge of the cover suchthat the spacer has a curved outer wall.
 3. An electronic apparatuscomprising the electro-optical device according to claim 1, wherein theelectronic apparatus includes a light source unit that irradiates themirror with light source light.
 4. An electro-optical device comprising:an element substrate including a mirror and a terminal on a firstsurface side, the terminal being provided at a position next to themirror in a plan view, the terminal being electrically connected to adrive element driving the mirror; and a sealing member including aspacer and a plate-like light-transmitting cover, the spacer beingbonded on the first surface side of the element substrate andsurrounding the mirror in the plan view, the light-transmitting coverbeing supported to an edge of the spacer on the side opposite to an edgethereof facing the element substrate, the light-transmitting coveroverlapping the mirror in the plan view, wherein in aside surface of thesealing member, a second portion closer to the element substrate than afirst portion is recessed to the mirror side beyond the first portion.5. The electro-optical device according to claim 4, wherein the firstportion that is recessed to the mirror side beyond the first portiondefines a recessed portion within an edge of the cover such that thespacer has a stepwise outer wall forming a gap between the cover and theelement substrate
 6. An electronic apparatus comprising theelectro-optical device according to claim 4, wherein the electronicapparatus includes a light source unit that irradiates the mirror withlight source light.